Homeostasis Flashcards
What is homeostasis :
The maintenance of a stable internal environment in the body despite change in the external environment
What factors dos the body need to keep constant?
- Carbon dioxide levels
- Waste removal
- Body temperature
- Oxygen levels
- Water content
- Glucose levels
- Blood sugar levels
- Heart rate
Integrator
Compares data from receptor and stored set point data and gives instructions to effector
Negative feedback:
Mechanism that counteracts and stops any further response.
Set point
The ideal/normal value of the variable
Response:
Corrective change that brings variable back to set point
Receptor/sensor:
Sensor that detects the change in the variable
Variable:
Characteristic that is controlled
Effector:
Brings about a corrective change
Stimulus:
A change in the variable
Egestion :
Removal of waste materials that have not been inside cells (involved in cell reactions e.g. fibres in faeces)
Excretion :
The removal of waste products of cell reactions from the body (e.g. water, mineral, urea, carbon dioxide)
Carbon Dioxide comes from …
- Product of aerobic respiration
- Removed through the lungs when we breathe out
Urea comes from…
- Produced in liver when excess amino acids are broken down (liver)
- Removed by kidneys from blood and make urine, stored temporarily in bladder
Salt comes from…
Removed by kidneys ans leaves body by urine
Water comes from …
-Through skin by sweat (product of respiration)
Waste is got rid of through :
- Mouth, skin, lungs and kidneys
Waste got rid of by mouth :
- Carbon dioxide
- Water
Waste got rid of by skin :
- Water
- Salt/mineral/ions
- Urea
Waste got rid of by lungs :
- Carbon dioxide
Waste got rid of kidneys :
- Water
- Mineral/Salt/Ion
- Urea
Why is osmoregulation so important ?
Osmoregulation keeps tha blood at a steady concentration, controlling water content
When water concentration in blood is too high…
If the blood is too dilute less water is absorbed from the kidney into the blood. The water then gets into the bladder as well. After drinking a lot, a large volume of dilute urine is produced
When water concentration in blood is too low…
If the blood is too concentrated more water is absorbed back into the blood from the kidney. So if your kidney is short of water, w.f after sweating a lot, only a small amount of urine is produced.
When carbon dioxide concentration in blood is too low …
Receptors in respiratory control centre of CNS in medulla sense low concentration. Respiratory control centre of the CNS does not send nerve impulses to diaphragm and intercoastal muscles. The diaphragm mad intercostal muscles relax and breathing rate drops so carbon dioxide levels can increase
When carbon dioxide concentration in blood is too high …
The receptors in the respiratory control centre of CNS in medulla sense high carbon dioxide concentration. Respiratory control centre of CNS sends nervous impulses to diaphragm and intercoastal muscles. Diaphragm and intercoastal muscles contract. The breathing rate will increase so that carbon dioxide levels will drop.
Thermoregulation :
The ability of the body to keep its temperature as close to 37 centigrade
Hyperthermia:
When the body temperature increase significantly above set point
Hypothermia:
When the body temperature decreases significantly below set point
What is the variable (thermoregulation)?
Core temperature
When would the variable provide a stimulus (thermoregulation)?
When body temperature is too high or too low
Where would you expect there to be receptors for this stimulus (thermoregulation)?
Sensors in skin and brain measure core body temperature by measuring the temperature of the blood flowing through the hypothalamus
What is the thermoregulation integrator?
Thermoregulatory centre in the brain
What is the set point for a human (thermoregulation)?
37 centigrade
Which parts of the body are effectors in thermoregulation?
Skin e.g. sweat glands
Muscles e.g. shiver
Skin responses such as …?
Temperature returns to set point 37 centigrade
What is negative feedback iand when does this occur in thermoregulation?
When the normal temperature is reached
Dermis :
Makes new epidermis at the top and contains all the nerves, blood vessels, sebaceous glands, sweat glands and hair roots.
Epidermis :
The outside of your skin. The top layer is dead and provides protection from dirt, germs and strong sunlight. The middle layer contain living cells. The bottom layer divides continually to provide new cell for epidermis.
Hair :
Made of keratin (protein)
Hair follicle :
Grows hair
Hair erector muscle :
Pulls the hair upright when the muscle contracts
Sebaceous gland :
Produces oily substances called sebum which makes the skin waterproof, prevents it from drying out and acts as a mild antisceptic to destroy fungi and bacteria.
Sensory nerves :
Helps you feel pain, pressure or temperature
Skin blood vessels :
Provides food + oxygen to the skin cells and helps regulate the body temperature
Subcutaneous layer :
Fatty tissue. Helps keep you warm+ protect your organs and bones from injury.
Sweet duct :
For transport of sweat from sweat gland to sweat pore
Sweat gland :
Produces sweat which contains 99.5% water, 0.25 urea and 0.25 sodium chloride
Sweat pore :
For sweat to come out. 3 X 10^^6 of these cover the human skin
When it’s too hot :
1) Hair lies flat do more heat is lost by radiation
2) Sweat glands open. The swear evaporates and this cools down.
3) Blood vessels at the skin surface widen (vasodilate). They allow more blood to flow to the surface. So more heat is lost by radiation
4) Changes in behaviour:
- undressing
- moving into shade
- resting
When it’s too cold :
1) The hair erector muscles contract pulling the hairs upright. This traps air which is a poor conductor of heart and so reduces heat loss.
2) Sweat glands close so no sweat is produced p
3) Blood vessels at the skin surface narrow (vasodilate). Less blood floss to the surface so less heat is lost by radiation
4) - Shivering
- Muscles produce extra heat
5) General increase in metabolic rate
6) Changes in behaviour :
- activity
- moving into sun
- dressing
The core temperature of the body has to be maintained …
At a temperature at which the enzymes work best.
Body temperature is controlled by …
The thermoregulatory centre in the hypothalamus, which has receptors that are sensitive to the temperature of the blood flowing through the brain
In addition, temperature sensors in the skin ….
Send impulses to the thermoregulatory centre to tell it about the change in temperature
If the core blood temperature is too high:
Blood vessels supplying the capillaries in the skin vasodilate so that more blood flows through them and more heat is lost. Sweat glands release swear through them and more heat is lost.sweat glands release swear which cools the body when it evaporates. More sweat is lost when it is hot, so extra fluid has to be taken is as liquids/drinks or foods to balance this loss. Also, the hairs on your skin lie flat, so more heat is lost be evaporation
If the core temperature is too low:
Blood vessels supplying the capillaries in the skin vasoconstrict, so that les blood flows through them and less heat is lost. Muscles may release heat by contraction. Thodi contraction requires respiration which releases some energy as heat. Loss of heat is prevents by the hairs on your skint standing upright. This traps air which is a poor conductor of heat.
When blood glucose levels is too high, (influences):
Glucose in food and drink is digested and absorbed into blood
When blood glucose levels is too low, (influences):
Glucose is taken out of blood into cells for use in respiration
Hyperglycemia can result in :
- Osmosis occurs and water diffuses out of the cells into the blood and water is excreted in urine
- Dehydration
- Coma + death
Hypoglycemia can result in :
- Not enough glucose for respiration
- Inadequate energy supply for brain cells
- Coma and death
What happens when you eat a bar of chocolate ?
Glucose is absorbed into bloodstream. Levels of glucose in blood are high. An crease detects these high levels and pancreas Secretes insulin into blood. The insulin is then carried in the bloodstream. Insulin binds to receptors on liver and muscles cells and they take up glucose. The glucose is converted into glycogen for storage. Blood glucose levels drop.
Why happens after running?
Rate of respiration increases and glucose is takes out of bloodstream. Pancreas detects low level of blood glucose. The pancreas secrets glycogen into blood. Glycogen is carried into bloodstream. Glycogen binds to receipts in liver and muscle cells, where it is converted into glucose. Muscle cells use glucose for respiration of release it into bloodstream and blood glucose levels rises.
What is diabetes?
Disorder when insulin is no longer able to lower blood glucose
What are symptoms of diabetes?
- high glucose in blood
- glucose in ruins
- excessive urine production
- dehydration and thirst
How can diabetes be diagnosed
- glucose in blood
- glucose in urine
Type 1 Diabetes (Juvenile Onset):
DOES NOT secrete insulin into blood (pancreas)
Insulin injection needed
Type 2 Diabetes (Adult Onset):
- Insulin DOES NOT bind to receptors on liver and muscle cells
- Regulation of diet
